Since Stephen Hawking discovered that black holes emit thermal radiation, black holes have become the theoretical laboratories for testing our ideas on quantum gravity. This dissertation is devoted to the study of ...

In this dissertation, I mainly focus on two subjects: (I) highly effective and efficient parameter estimation algorithms and their applications to cosmology; and (II) the late cosmic acceleration of the universe in string/M ...

In this thesis, I first review the fundamentals of Hot Big Bang cosmology, the observational cosmology and the late
accelerating universe. Then I systematically study the evolution of the Friedmann-Robertson-Walker (FRW) ...

A systematic study of space-times containing two timelike colliding branes is made, in the framework of 10-dimensional string theory. After developing the general formulas to describe such events, we study several classes ...

In this thesis, the gravitational collapse of the Brans-Dicke scalar field and formation of black holes in 2+1 Gravity is examined. In contrast to general relativity, there are two conformally related frames in the ...

In this thesis, I first review the fundamentals of Einstein's theory of gravity in four-dimensional spacetimes, and then develop the general formulas of thin shells in this theory. Applying these formulas to spherically ...

In this dissertation, I studied Hořava-Lifshitz gravity and its applications to inflationary cosmology. After introducing the original proposal with the projectability and detailed balance conditions, I discussed its ...

This dissertation contains two distinct compactification schemes of 10-dimensional string theory, as well as some of the implications of one of these schemes for string cosmology. The first half of this work begins with a ...